F! is half an hour, and then everyone has to get OUT of the theatre. That can take well more than 15 minutes, and the F! theatre does not have a good fireworks view.
I've not ever read that anyone has missed any of the Star Wars fireworks after F! if their intension was to see them both.
(Yes, the timing looks to be 15 min. closer than in the recent past, but I'm thinking that they may delay the start of the actual fireworks
a bit longer than they have them booked.)